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Browse Prior Art Database

Features That Allow a Comprehensive Card Self-Test

IP.com Disclosure Number: IPCOM000102094D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 85K

Publishing Venue

IBM

Related People

Martin, GR: AUTHOR

Abstract

Disclosed are a number of features incorporated on a logic card to allow it to perform a comprehensive self-test. Test coverage was required to be equal to, or better than, the coverage of a stuck fault test. The self-test had to be performed with a minimum of external hardware, not on a functional tester and be capable of producing diagnostic information that identified any failing component(s).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Features That Allow a Comprehensive Card Self-Test

       Disclosed are a number of features incorporated on a
logic card to allow it to perform a comprehensive self-test.  Test
coverage was required to be equal to, or better than, the coverage of
a stuck fault test.  The self-test had to be performed with a minimum
of external hardware, not on a functional tester and be capable of
producing diagnostic information that identified any failing
component(s).

      A microprocessor, ROM-containing self-test code and a serial
diagnostic interface are all incorporated into one chip.  This allows
the processor to boot-up, execute its own self-test and report the
status of this test independently from the rest of the card.  Fault
diagnosis and isolation are difficult in these areas because they
will be the first areas tested and, if an error does occur, the test
will often come to a complete halt and provide no diagnostic
information. Previous designs have shared these functions between
different chips and, in the event of a fault occurring in one of
these areas, fault diagnosis and isolation have been more difficult
and less accurate.  If an error does occur early in self-test and
diagnostic information is not available, the fault can be identified
as being in the microprocessor chip.

      Microcode necessary to test all parts of the card and report
the status of the tests is made resident on the card itself.
Although the microprocessor self-test code is implemented within the
microprocessor module and itself (as described above), the remainder
of the self-test code is stored in EPROM on the card.  The test code
is based on the product BATs.  In order to invoke it, the test rig
has only to pull down a single card input.  Advantages exist in
having all of the self- test code resident on the card under test: if
any ECs are required on the card, then it is only necessary to change
the resident test code. No detailed knowledge of the card under test
is need...